Adolescent Addiction Centers Light Up on Cue

TORONTO – Functional magnetic resonance imaging has shown that even very low levels of nicotine exposure can cause detectable changes in the adolescent brain's addiction centers, some of which differ from nicotine-related changes seen in adult brains, a study showed.

Previous research has also revealed differences in the effects of smoking on adolescents, compared with adults, Dr. Mark L. Rubinstein of the University of California, San Francisco, said at the meeting.

“We know that people who start smoking as teenagers are more likely to become lifelong smokers than those who start smoking as adults. In addition, teens seem to be more susceptible to nicotine addiction, reporting addiction with much lower levels of smoking–sometimes even without smoking daily.”

Pharmacotherapy for smoking cessation is also less effective in teens than in adults. The current research aimed to discover underlying brain effects that might account for these differences.

In adult smokers, functional MRI has shown that both nicotine and smoking cues produce activity in the mesolimbic addiction system, specifically in the amygdala, the orbital frontal complex, the hippocampus, and the prefrontal cortex. Previous studies of heavy smokers in their teens found similar results. However, because the majority of adolescents smoke only two to five cigarettes per day, Dr. Rubinstein's research used 12 light smokers (one to five cigarettes per day [mean 3.6] for at least 6 months) aged 13-17, along with 12 smoking-naive adolescents of the same age as controls.

“We wondered if this might give us a better indication of the way adolescent brains work, and also a better idea of how early addiction processes work in the brain,” he said.

Because cue exposure has the same effects on brain activity as actual nicotine, participants passively viewed a set of smoking-related images, then a set of neutral images, with process repeated eight times.

Functional analysis of their brains during this process found that nonsmokers showed no brain activation in any area.

In smokers, however, smoking cues were significantly associated with activity in the anterior cingulate (in the frontal cortex), the middle occipital gyrus, and the hippocampus–all of which lie within the brain's addiction centers.

“The hippocampus is involved with memory, specifically drug reward memories and conditioned responses,” Dr. Rubinstein said. “The cingulate gyrus, which is in the frontal lobe, is involved in inhibitory control, and importantly, the frontal cortex, specifically the prefrontal cortex, is the last part of the teenage brain to develop.

The medial occipital lobes are involved in visuospatial processing; this is subtracting the activation that occurs when smokers stare at neutral images, so they're paying more attention to the smoking images, which is no surprise but has been associated with addiction in adults.”

Although these results were similar to those seen in adult smokers, a significant difference was found: In adults, the lateral orbital frontal complex is usually activated, but in these teenaged light smokers, the medial orbital frontal complex was affected.

“The orbital frontal complex is involved in reward-related learning and impulse control, and a lot of people think that the medial orbital frontal complex might be the most important in impulse control,” said Dr. Rubinstein.

“One of our theories is that the medial orbital frontal complex may be important in the development of addiction rather than the maintenance of addiction.”

This is supported by the observation that these teen smokers scored only 2.8 on the modified Fagerström Tolerance Questionnaire, indicating no or very light addiction.

“Clinically, this says to us that even at very light/low levels of nicotine exposure, you may already be causing changes in the brain,” he concluded.

Dr. Rubenstein reported no relevant financial relationships.

In teen smokers, smoking cues were significantly associated with activity in the brain's addiction centers.

Source Images courtesy Dr. Mark L. Rubinstein

TORONTO – Functional magnetic resonance imaging has shown that even very low levels of nicotine exposure can cause detectable changes in the adolescent brain's addiction centers, some of which differ from nicotine-related changes seen in adult brains, a study showed.

Previous research has also revealed differences in the effects of smoking on adolescents, compared with adults, Dr. Mark L. Rubinstein of the University of California, San Francisco, said at the meeting.

“We know that people who start smoking as teenagers are more likely to become lifelong smokers than those who start smoking as adults. In addition, teens seem to be more susceptible to nicotine addiction, reporting addiction with much lower levels of smoking–sometimes even without smoking daily.”

Pharmacotherapy for smoking cessation is also less effective in teens than in adults. The current research aimed to discover underlying brain effects that might account for these differences.

In adult smokers, functional MRI has shown that both nicotine and smoking cues produce activity in the mesolimbic addiction system, specifically in the amygdala, the orbital frontal complex, the hippocampus, and the prefrontal cortex. Previous studies of heavy smokers in their teens found similar results. However, because the majority of adolescents smoke only two to five cigarettes per day, Dr. Rubinstein's research used 12 light smokers (one to five cigarettes per day [mean 3.6] for at least 6 months) aged 13-17, along with 12 smoking-naive adolescents of the same age as controls.

“We wondered if this might give us a better indication of the way adolescent brains work, and also a better idea of how early addiction processes work in the brain,” he said.

Because cue exposure has the same effects on brain activity as actual nicotine, participants passively viewed a set of smoking-related images, then a set of neutral images, with process repeated eight times.

Functional analysis of their brains during this process found that nonsmokers showed no brain activation in any area.

In smokers, however, smoking cues were significantly associated with activity in the anterior cingulate (in the frontal cortex), the middle occipital gyrus, and the hippocampus–all of which lie within the brain's addiction centers.

“The hippocampus is involved with memory, specifically drug reward memories and conditioned responses,” Dr. Rubinstein said. “The cingulate gyrus, which is in the frontal lobe, is involved in inhibitory control, and importantly, the frontal cortex, specifically the prefrontal cortex, is the last part of the teenage brain to develop.

The medial occipital lobes are involved in visuospatial processing; this is subtracting the activation that occurs when smokers stare at neutral images, so they're paying more attention to the smoking images, which is no surprise but has been associated with addiction in adults.”

Although these results were similar to those seen in adult smokers, a significant difference was found: In adults, the lateral orbital frontal complex is usually activated, but in these teenaged light smokers, the medial orbital frontal complex was affected.

“The orbital frontal complex is involved in reward-related learning and impulse control, and a lot of people think that the medial orbital frontal complex might be the most important in impulse control,” said Dr. Rubinstein.

“One of our theories is that the medial orbital frontal complex may be important in the development of addiction rather than the maintenance of addiction.”

This is supported by the observation that these teen smokers scored only 2.8 on the modified Fagerström Tolerance Questionnaire, indicating no or very light addiction.

“Clinically, this says to us that even at very light/low levels of nicotine exposure, you may already be causing changes in the brain,” he concluded.

Dr. Rubenstein reported no relevant financial relationships.

In teen smokers, smoking cues were significantly associated with activity in the brain's addiction centers.

Source Images courtesy Dr. Mark L. Rubinstein

TORONTO – Functional magnetic resonance imaging has shown that even very low levels of nicotine exposure can cause detectable changes in the adolescent brain's addiction centers, some of which differ from nicotine-related changes seen in adult brains, a study showed.

Previous research has also revealed differences in the effects of smoking on adolescents, compared with adults, Dr. Mark L. Rubinstein of the University of California, San Francisco, said at the meeting.

“We know that people who start smoking as teenagers are more likely to become lifelong smokers than those who start smoking as adults. In addition, teens seem to be more susceptible to nicotine addiction, reporting addiction with much lower levels of smoking–sometimes even without smoking daily.”

Pharmacotherapy for smoking cessation is also less effective in teens than in adults. The current research aimed to discover underlying brain effects that might account for these differences.

In adult smokers, functional MRI has shown that both nicotine and smoking cues produce activity in the mesolimbic addiction system, specifically in the amygdala, the orbital frontal complex, the hippocampus, and the prefrontal cortex. Previous studies of heavy smokers in their teens found similar results. However, because the majority of adolescents smoke only two to five cigarettes per day, Dr. Rubinstein's research used 12 light smokers (one to five cigarettes per day [mean 3.6] for at least 6 months) aged 13-17, along with 12 smoking-naive adolescents of the same age as controls.

“We wondered if this might give us a better indication of the way adolescent brains work, and also a better idea of how early addiction processes work in the brain,” he said.

Because cue exposure has the same effects on brain activity as actual nicotine, participants passively viewed a set of smoking-related images, then a set of neutral images, with process repeated eight times.

Functional analysis of their brains during this process found that nonsmokers showed no brain activation in any area.

In smokers, however, smoking cues were significantly associated with activity in the anterior cingulate (in the frontal cortex), the middle occipital gyrus, and the hippocampus–all of which lie within the brain's addiction centers.

“The hippocampus is involved with memory, specifically drug reward memories and conditioned responses,” Dr. Rubinstein said. “The cingulate gyrus, which is in the frontal lobe, is involved in inhibitory control, and importantly, the frontal cortex, specifically the prefrontal cortex, is the last part of the teenage brain to develop.

The medial occipital lobes are involved in visuospatial processing; this is subtracting the activation that occurs when smokers stare at neutral images, so they're paying more attention to the smoking images, which is no surprise but has been associated with addiction in adults.”

Although these results were similar to those seen in adult smokers, a significant difference was found: In adults, the lateral orbital frontal complex is usually activated, but in these teenaged light smokers, the medial orbital frontal complex was affected.

“The orbital frontal complex is involved in reward-related learning and impulse control, and a lot of people think that the medial orbital frontal complex might be the most important in impulse control,” said Dr. Rubinstein.

“One of our theories is that the medial orbital frontal complex may be important in the development of addiction rather than the maintenance of addiction.”

This is supported by the observation that these teen smokers scored only 2.8 on the modified Fagerström Tolerance Questionnaire, indicating no or very light addiction.

“Clinically, this says to us that even at very light/low levels of nicotine exposure, you may already be causing changes in the brain,” he concluded.

Dr. Rubenstein reported no relevant financial relationships.

In teen smokers, smoking cues were significantly associated with activity in the brain's addiction centers.

Source Images courtesy Dr. Mark L. Rubinstein